Loperamide is a safe and effective antidiarrheal for the treatment of acute diarrhea. Efficacy data suggest that loperamide is more effective than the prescription drug diphenoxylate and an over-the-counter bismuth subsalicylate preparation. Loperamide is a safe drug, with few adverse reactions reported worldwide. It also lacks significant abuse potential. Loperamide may prove to be the antidiarrheal agent of choice when compared with currently available nonprescription treatments for acute diarrhea.